DESCRIPTION (Applicant's Abstract): Prior research from our laboratory has developed a non-human private model of fearful temperament and has defined the associated physiological characteristics. Human neuroimaging studies implicate the amygdala in mediating fear-related psychopathology and yet little is known,a t a mechanistic level, regarding how the amygdala is involved in mediating fear responses in the primate. In the current proposal we will examine the role of amygdala glutamate, GABA, and CRF systems in mediating the primate's fear-related responses. A variety of techniques will be used: reversible inactivation of amygdala neurons, intra-amygdaloid administration of agents affecting glutamate, GABA, and CRF neurotransmitter systems, and push-pull perfusion to assess endogenous release of these neurotransmitters. Finally, we will use these techniques to investigate the role of these neurotransmitter systems in mediating individual differences in fearful temperament.